Guide
Insurance requirements for a plumbing subcontractor
A plumbing failure rarely damages the plumbing. It damages everything under it — which is why this trade turns on resulting damage rather than on the work itself.
Require the usual coverages, then ask specifically what the policy says about water damage and about damage to the work itself, which most general-liability policies exclude.
Key takeaways
- The loss is almost never the pipe. It is the floor, the ceiling below, the drywall, the cabinetry and the tenant's stock. That is resulting damage, and it is where the money is.
- Damage to their own work is usually excluded, and that is normal. A general-liability policy is not a warranty. What you are checking is that damage to other property is covered, not that the failed joint is.
- Plumbing is licensed at state level and often at city level too. A GL certificate says nothing about whether the license is current, and an unlicensed installation can void the coverage that would otherwise respond.
- Ask about the completed-operations aggregate as well. A leak found after handover behaves like the roofing case; that argument lives on the roofing page rather than being repeated here.
- Your contract sets the limit. A guide that prints one has not seen your building.
By the Sealinn team · 2 min read · Updated August 2026 · Written for general contractors
Resulting damage is the whole question
When a supply line lets go on the fourth floor, the plumbing is the cheapest thing that gets replaced. The claim is the water's path through the building, and it is frequently an order of magnitude larger than the contract value of the plumbing work itself. That is the exposure a general contractor is carrying when they hire a plumber, and the certificate's per-occurrence limit is the number to weigh against it — not the value of the subcontract.
The distinction that matters on the policy is between damage to their work and damage caused by their work. The first is generally excluded from a commercial general-liability policy, and that exclusion is standard rather than a red flag — GL is not a workmanship warranty. The second is the coverage you are relying on, and it is what to confirm is intact.
Ask the question in writing, before the job
“Does this policy carry any water-damage exclusion, sub-limit or deductible that differs from the general per-occurrence limit shown?” An agent can answer that in one line, and the answer belongs in the file next to the certificate rather than in somebody's memory.
The license, which is not optional and not on the COI
Plumbing is one of the trades where licensing is genuinely enforced, usually by a dedicated state board rather than by a general contractor registry — Texas, for example, runs a separate State Board of Plumbing Examiners. A lapsed license is a live problem in two directions: the work may fail inspection, and an insurer may decline a claim arising from work performed without the license the state required.
None of that appears on an ACORD 25, which is a statement about insurance and nothing else. Verifying it is a separate step, and contractor license verification covers how to do it and where the public lookups are.
The rest of the certificate, and the other trades
Everything not specific to plumbing — the coverages, the endorsements, the waiver, the paperwork you collect alongside — is on what to require before a sub starts. For roofing the line to read is products-completed operations; for excavation it is the XCU exclusion.
Where this comes from
- ACORD — Certificate of Liability Insurance (form 25)
- ISO — Commercial General Liability Coverage Form (CG 00 01 occurrence / CG 00 02 claims-made)
- Texas State Board of Plumbing Examiners — Licensing and regulation of the plumbing trade for the State of Texas
- National Association of State Contractors Licensing Agencies — State licensing information and the contractor state licensing directory
The four jobs, done for you.
Sealinn reads each certificate, checks it against your rules, chases renewals before they lapse, and keeps the record.